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Poster: leftwinger57 Date: Feb 24, 2012 5:03pm
Forum: GratefulDead Subject: the wall and how was it wired

Hi guys, As most of you know I'm more into the gear that the band used and improved over the years than the dates,venues,set lists, or when a certain solo hits and other minutia that I know loads of you eat up but I'm not one of them.What interests me is how the hell did they wire 500 and change 15'',12' JBL,Gauss speakers and assorted other sized speakers not to mention the 2 huge tweeter arrays.I realize that there were some 89 McIntosh 2300 amps for pa alone plus the Macs for the instruments.So how does anybody wire that many speakers and not only make it work but work so well that it was the industries finest for some time until got to big and they had to leapfrog the sets and 2. Pink Floyd's sound system came into it's own.Also remember that Phil's bass was quadraphonic and each string and or pick/up came out of different speakers set at differing levels.Today it would be called a line array p.a. but they were the first to impliment the theory.I get a headache just adjusting and messing w/ my own rack and it's about 1000th the size w/ only 10 speakers.

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Poster: leftwinger57 Date: Feb 25, 2012 2:50pm
Forum: GratefulDead Subject: Re: the wall and how was it wired

DHmonty,See you ask a normal question and the response is terrific.The articles are amazing and I can't wait to get that Blair Jackson book on their gear.It mattered so much to so many people and to think it all started w/ a couple of Fender Twins a Bass bottom a Farfisa organ and a pretty small drum kit. Now that's progress for you.

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Poster: Dhamma1 Date: Feb 25, 2012 6:32am
Forum: GratefulDead Subject: Re: the wall and how was it wired

If dark.starz's links don't answer your questions, Blair Jackson spent a whole chapter (pages 131-150) on the Wall of Sound in his 2006 book "Grateful Dead Gear"

I think it's out of print now, but the nearest public library can get it for you if you ask them. Or if you want, I'll copy that chapter for you -- mmiedmonds at gee mail

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Poster: leftwinger57 Date: Feb 25, 2012 7:23am
Forum: GratefulDead Subject: Re: the wall and how was it wired

Dhamma1, Now this is the kind of book I'm looking for.It looks very extensive and clearly goes into the tech detail that I'm after .Thanks alot and I'll let you know if I can get it or not. Around here if one library doesn't have a certain book they have mutual aid lending service kinda like fire depts. if you know what I mean. Right now I'm reading Fail-Safe and I think the movie was great but of course the book delves into more of the personalities of all involved that fateful day.

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Poster: dead-head_Monte Date: Feb 25, 2012 2:12pm
Forum: GratefulDead Subject: Re: the wall and how was it wired

David Gans laughing when he's reading my comments about "Alembic and the GD crew wiring the GD's Wall of Sound PA System in 1973"
david_gans.jpgThe wiring from their amplifiers to their speakers could have been an ongoing combination of series and parallel circuits. In theory, these differing impedance combinations for their speaker arrays might have depended upon each particular venue. Why? Achieving the optimal desired sound pressure level at each venue would have been done differently at each venue. Theoretically, each venue's size, stage, and seating would have dictated the number of speakers needed at each venue. This determines how things were configured. The crew achieved the desired sound quality, dynamic range, clarity, and loudness that GD and Alembic were famous for. Therefore, the number of amplifiers used at each venue probably depended upon how many speakers were being used, and how they were being arrayed. I believe the wiring requirements would have been determined by how Alembic and GD's crew configured their PA System at each venue. The 1973 outdoors venues were large, and some of them were huge. Indoor venues were smaller. My theory could be totally wrong regarding how the engineering managers approached this stuff. Obviously, equipment availability for each venue was another factor to consider. Turnaround times for striking the PA at the end of their last gig, and then setting it up again at the next gig, between venues, would have been the crucial factor. Sometimes they borrowed extra equipment, as was the case at Watkins Glen: "The crowd was so huge that a large part of the audience was not able to see the stage; however, twelve huge sound amplifiers, installed courtesy of legendary promoter Bill Graham, allowed the audience to at least hear." - from Wikipedia | headline below appeared on Sunday, July 29, 1973.
I think that Rhino could have David Lemieux hire Charlie Miller and me for a June 1973 RFK Stadium project. Rhino could be the first commercial media outfit in the 21st century world to roll out a multi-DVD-type "single-venue box" release that includes:

• 2 SBDs, 2 MTXs, 2 DTSs, and 2 AUDs • interviews with the tapers and filmmakers • interviews with the recording and sound engineers • interviews with fans who attended this venue • additional photos and films • additional venue documentation such as PDFs • SBDs, MTXs, DTSs and Videos - available for commercial download; AUDs are free The audio tape reels for these shows should be baked, transferred again, pitch corrected again, and remastered again. Photos and films need to be collected to see what we have to work with. Getting the Allman Brothers Band involved with this project would take it to its proper place in history. Rhino could be the first outfit in the world to successfully bring tapers into the fold on a commercial release without tarnishing anything. I sure would appreciate it if GD fans would contact Rhino and David Lemieux about this. Thanks. • discussion with Charlie Millerstory about taping Grateful Dead at RFK Stadium in June 1973Monte's Taper CompendiumAlembic articles are in this Bear-Gans interview item

Lossless Legs recently circulated a memorabilia torrent. That's where the David Gans photo, above, comes from. This torrent also includes what I've reproduced below. I had to edit this a few times to include this stuff, and to get the credits in there. The first item below is what appears to me to be a "newsletter" produced by Alembic. I'm guessing at this, but I'll bet Alembic circulated this, and it was probably in every music store in the country. The second item below, Grateful Dead Wired for Sound by Jim Aikin, is reproduced "as is" and all I did was to cut it up differently to make it more presentable on a web page here. I do not have the source and date for this article.






This post was modified by dead-head_Monte on 2012-02-25 22:12:27

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Poster: deadpolitics Date: Feb 25, 2012 10:45am
Forum: GratefulDead Subject: Re: the wall and how was it wired

Ahhhh! Thank you! Where is page 34 with continuation of pink noise discussion??

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Poster: AltheaRose Date: Feb 26, 2012 5:48am
Forum: GratefulDead Subject: Re: the wall and how was it wired

Really interesting. The parts I understood, anyway :-)

Favorite quote: "We want a clean sound. It makes you feel better." I like that being a musical goal!

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Poster: dark.starz Date: Feb 25, 2012 10:46pm
Forum: GratefulDead Subject: Re: the wall and how was it wired

" if they were in parallel w/ one giant splice per bank to amps how many speakers I'm not so .sure Series on the other hand would more than likely take the load off but if a speaker goes out then I think that whole bamk goes w/ it. "

The McIntosh MC-2300 power amplifiers incorporated their proprietary “autoformer” output transformer technology yielding a very stable 300 watt stereo/600 watt mono solid state amplifier incorporating six different impedance matching terminals 0.5, 1, 2, 4, 8 and 16 ohm taps.

It has been mentioned that the Dead used 48 MC-2300's to power the Wall. Jerry and Bob’s guitar were one amp each, Phil’s quad bass used four each, Bill’s drums used three amp channels, etc.

Take for example the vocal clusters, just one half of this array incorporated approximately 60 JBL 5" drivers and 30 JBL 12" drivers. Assuming that the nominal impedance of each driver is 8 ohms, two each in parallel would equal approximately 4 ohms, three would equal approximately 2.5 ohms, four each would present a load somewhere @ 2 ohms. I would be shocked if they ran these amps into a load below 2 ohms.

Personally, I’d keep the load at 4 ohms, but assuming they dipped down to 2 ohms would require 7.5 MC-2300 amp channels just to drive half of the 5" drivers in the vocal array if they were wired in parallel and 3.75 MC-2300 amp channels to drive half of the 12" drivers. This equates to 22.5 MC-2300's to drive the full vocal array in parallel. The sixteen JBL 15" vocal enclosures would require two additional MC-2300's for a total of 24.5 MC-2300's just for the vocal system. The tweeters were driven by a McIntosh tube amplifier.

There are eight additional hybrid vocal enclosures on stage incorporating two JBL 12" and six JBL 5" drivers. There could be a crossover network inside these enclosures to maintain a higher impedance so conservatively four additional amp channels, that’s 26.5 MC-2300's.

Keith’s piano array incorporated 32 JBL 12" drivers that’s eight MC-2300 channels and approximately 80 JBL 5" drivers in parallel would require twenty MC-2300 amp channels. The piano fill enclosures would require six additional MC-2300 channels if wired in parallel, that’s 40.5 MC-2300's. I see a cabinet with eight MC-2300's on stage left where Keith’s piano resided, therefore some series wiring is possible for Keith.

Further, Phil had four MC-2300 amps driving two columns of 18 each JBL 15" drivers for a total of 32, that’s eight MC-2300 amp channels driving 4 JBL 15" drivers each and a much more difficult load when compared to the 5" drivers. That’s 44.5 MC-2300's.

Add Jerry and Bob’s two amps driving 20 each JBL 12" drivers?, add Bill’s three amp channels and you are exactly at 48 McIntosh MC-2300's. How is it possible to drive 20 JBL 12" drivers with a single MC-2300? Therefore, it’s logical to assume that Jerry and Bob ran their amps in mono generating some 600 watts.

Somewhere within this system it’s reasonable to assume that some of the drivers were wired in series. The wiring harness must have been incredibly rigid, hopefully with locking connectors. Do you realize how much electrical current would be required just to power up all these amplifiers? Did the Dead travel with multiple power generators?

Add to the mix, two separate systems, one assembled on any given day for the evenings performance as the second unit traveled to next venue. It’s no wonder why they went bust.

“ Thanks for the attempt but we need an audio engineer who knows for sure how it was done. “

Not really, just the schematic will do. It’s really not that difficult to do the math. However it did require the minds of John Curl, Dick Burwen, Bear, Healy, Rick Turner etc. to engineer the system from the ground up.

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Poster: dead-head_Monte Date: Feb 26, 2012 7:38am
Forum: GratefulDead Subject: Re: the wall and how was it wired

BudMan.JPG"For a very brief time at the end of 1972, Jerry began to power his speakers with Mcintosh MC3500 tube power amps. The input buffer stage of the MC3500 was bypassed and the Twin's Preamp signal was fed straight to the Output Stage. In this configuration only 1 Fender Twin cabinet was used and both the Normal and Vibrato channels Preamp tapped to individual MC3500's. By 1973 he was using the MC2300 solid state amplifier for power with a single Fender Twin Reverb cabinet with both Vibrato and Normal channels Preamp tapped. Again, this produced half the output with reverb and the other half without." "From the early days, to the end of the "Wall of Sound" in 1974, the work done to Jerry's Twin(s) was done by Alembic and the "Alembicization" mods were done to them. During the "Wall of Sound" he used a Blackface Twin, Alembic Preamp Tap. Both channels were jumpered together with a jumper cable from the Vibrato channel Input 2 to the Normal channel input 1. The Guitar used input 1 of the Vibrato channel and the jumper cable connection allowed for the one signal to pass to both preamps. Each channel was preamp tapped seperately to each side of an MC2300. Once again producing reverb on only half the total output. A Budweiser "Bud Man" Sticker is placed on Jerry's MC2300 and this particular amp becomes a favorite of his that he would use almost throughout the rest of his onstage performances." "Jerry's main Mcintosh MC2300, "Bud Man", was a remnant from the Wall of Sound. It was modded by Alembic with 1/4" input jacks versus the stock RCA jacks. Alembic also did the Banana Plug speaker jack modifications as well as configuring supports that held the amp chassis and the rack mounting rails to handle the rigors of touring. Later, Dan Healy stated it was modded to have its Mcintosh Sentry Monitor (VI Current Limiter) disengaged/removed from the Driver Cards as well as "Hand Matched" Driver Transistors and Emitter resistors. The Filter Capacitors Cans were custom made with a Higher Capacity and Voltages were increased for better filtering. The Output Transistors were Motorola 2n5303's, also "Hand Matched" with a curve tracer. Jerry used the 2 ohm tap of the MC2300, in Stereo Mode, using the Left Channel. The 12" JBL speakers were banana plugged in parallel."

web page for The History of Alembicization of Jerry's rig


Wall of Sound MC2300 amplifier shown above and below is fitted with Alembic Mods


Wald-Electronics © 2009 All Rights Reserved
Alembicization Notes PDF - Courtesy of Janet Bowman


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Poster: dark.starz Date: Feb 26, 2012 11:14pm
Forum: GratefulDead Subject: Re: the wall and how was it wired

Having stood at the foot of the platform stage and scaffolding of the "The Wall" in Des Moines on June 16th, 1974 there is no freakin way that Garcia filled the fairgrounds that wonderful afternoon with only 300 watts of power.

No flusin way!

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Poster: dark.starz Date: Feb 24, 2012 9:46pm
Forum: GratefulDead Subject: Re: the wall and how was it wired

Several of those clusters must have been wired in series, yes?

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Poster: leftwinger57 Date: Feb 25, 2012 1:08am
Forum: GratefulDead Subject: Re: the wall and how was it wired

if they were in parallel w/ one giant splice per bank to amps how many speakers I'm not so .sure Series on the other hand would more than likely take the load off but if a speaker goes out then I think that whole bamk goes w/ it.
I was an alarm installer for years and the general rule for closed circuit contacts is to be wired in series, again if one door/window opens it sets off the alarm.With fire and panic alarms it's wired in parallel so any device will work and all others would would also Speakers do have resistance 8ohms ect.So how many speakers per bank of amps were wired.I would have loved to see the back of that stage.Not to mention the power needed. As a oft story when I saw Pink Floyd at Yankee Stadium all along Jerome Ave. they had rows of semi trailer generater trucks just puming all the juice that was required. These shows plug strip need not apply.Thanks for the attempt but we need an audio engineer who knows for sure how it was done.